A combined heat and power system and method for achieving flexible peak regulation of a nuclear power unit

Abstract

The present application relates to the technical field of new energy power generation and energy storage, and particularly relates to a cogeneration system and method for realizing flexible peak regulation of a nuclear power unit. Heat and electricity are decoupled through heat storage, and the waste heat of the power plant is comprehensively recovered. The heat pump is used to increase the temperature to realize the conversion of electricity and heat, and the ORC generator unit is coupled to assist power peak regulation. During the peak electricity consumption period, the nuclear power unit generates electricity at full capacity, the high-temperature heat storage tank is used as a high-temperature heat source to drive the ORC unit to generate electricity or supply heat externally, the released heat is returned to the medium-temperature heat storage tank for storage, and the waste heat of the exhaust steam during power generation is stored in the low-temperature heat storage tank. During the valley electricity consumption period, as much steam as possible is extracted for heat storage, and the heat pump is driven by the generated electricity to supply heat after the waste heat of the exhaust steam and the waste heat stored during the peak period are increased in temperature by the heat pump, and the excess high-temperature heat is stored. In this way, the heat supply capacity is improved, and the depth of the power peak regulation is realized. The entire cogeneration system can be flexibly adjusted and operated according to the changes in the heat and electricity loads.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy power generation and energy storage, and particularly relates to a combined heat and power system and method for realizing flexible peak regulation of a nuclear power unit. BACKGROUND

[0002] Due to the limitation of nuclear island safety factors, the power regulation range of a nuclear power unit is small, and the variable load rate is slow, so the nuclear power unit generally operates at a rated operating condition and basically does not participate in peak regulation. Nuclear combined heat and power can not only avoid waste of nuclear power resources, but also reduce the nuclear safety risk caused by rapid and large fluctuations in reactor power, and can realize peak regulation of nuclear power while supplying power and heat, and reduce carbon emissions in the field of power generation and heat supply.

[0003] In the related art, when nuclear power supplies heat, part of high-quality steam needs to be extracted from the nuclear power unit, and the power of the unit will change with the change in the extraction amount of steam. Increasing the extraction of steam for heat supply will cause the power generation of the nuclear power unit to linearly decrease, and the heat and power loads are respectively affected by user-side demand and are not inversely proportional to each other. The combined heat and power unit has problems such as heat and power coupling and low regulation flexibility. In addition, the heat of the high-quality steam used for combined heat and power after one conversion is not fully utilized, and a large amount of waste steam waste heat is discharged to the environment, and the comprehensive utilization rate of nuclear energy is low.

[0004] Therefore, there is an urgent need to provide a combined heat and power system and method for realizing flexible peak regulation of a nuclear power unit to solve the above technical problems. SUMMARY

[0005] In order to solve the problems that nuclear power cannot frequently regulate peak, heat and power are coupled during combined heat and power, and a large amount of waste steam waste heat is wasted, the present application provides a combined heat and power system and method for realizing flexible peak regulation of a nuclear power unit.

[0006] In a first aspect, the embodiments of the present application provide a combined heat and power system for realizing flexible peak shaving of a nuclear power unit, comprising a steam turbine, a condenser, a steam-water heat exchanger, a heat pump unit, a low-temperature thermal storage tank, a medium-temperature thermal storage tank, a high-temperature thermal storage tank and an ORC generator set, the steam turbine is connected with the steam inlet and outlet of the steam-water heat exchanger through a steam extraction pipeline and a drain pipeline, the exhaust steam pipeline of the steam turbine is connected with the condenser, the condenser is connected with the evaporator side inlet and outlet of the heat pump unit and the inlet and outlet of the low-temperature thermal storage tank through a cooling circulating water pipeline, the condenser side water inlet of the heat pump unit is connected with a hot water return pipeline, the condenser side water outlet is connected with a hot water supply pipeline and the water inlet pipeline of the steam-water heat exchanger, the inlet and outlet pipelines of the medium-temperature thermal storage tank are connected with the hot water return pipeline, the water inlet pipeline of the steam-water heat exchanger and the evaporator side water outlet pipeline of the ORC generator set, and the inlet and outlet pipelines of the high-temperature thermal storage tank are connected with the water outlet pipeline of the steam-water heat exchanger, the hot water supply pipeline and the evaporator side water inlet pipeline of the ORC generator set.

[0007] In a second aspect, the embodiments of the present application provide a combined heat and power method for realizing flexible peak shaving of a nuclear power unit, which is applied to the method of the above-mentioned embodiments, during a power consumption peak period, the adjusting valves of the steam extraction pipeline, the drain pipeline, the water inlet and outlet pipelines of the steam-water heat exchanger, the evaporator side inlet and outlet pipelines and the condenser side inlet and outlet pipelines of the heat pump unit are closed, and the adjusting valves of the inlet and outlet pipelines of the low-temperature thermal storage tank are opened, at this time, the nuclear power unit generates power at full capacity, the waste heat of the exhaust steam of the steam turbine after power generation is stored in the low-temperature thermal storage tank through heat exchange of the condenser and the cooling circulating water pipeline;

[0008] During a power consumption valley period, the adjusting valves of the steam extraction pipeline, the drain pipeline, the water inlet and outlet pipelines of the steam-water heat exchanger, the evaporator side inlet and outlet pipelines and the condenser side inlet and outlet pipelines of the heat pump unit are opened, and the adjusting valve of the evaporator side inlet and outlet pipelines of the ORC generator set is closed, the high-temperature steam extracted from the steam turbine enters the steam-water heat exchanger through the steam extraction pipeline, heats the outlet water of the medium-temperature thermal storage tank, returns to the exhaust steam pipeline of the steam turbine and enters the condenser for continuous cooling, the heat of the high-temperature steam is stored in the high-temperature thermal storage tank through the steam-water heat exchanger, the waste heat of the exhaust steam is exchanged to the cooling circulating water through the condenser, and the heat stored in the low-temperature thermal storage tank is released at the same time, which is recovered as the low-temperature heat source of the heat pump unit.

[0009] The embodiment of the present application provides a kind of heat and power cogeneration system and method for realizing flexible peak regulation of nuclear power unit, heat is stored to realize heat and electricity decoupling, while comprehensively recovering power plant waste heat, temperature is raised using heat pump to realize electricity and heat conversion, coupled ORC generator unit auxiliary power peak regulation.In peak electricity consumption period, nuclear power unit generates electricity at full capacity, high-temperature heat storage tank is used as high-temperature heat source to drive ORC unit to generate electricity or supply heat to outside, and hot water is returned to medium-temperature heat storage tank for storage after heat release (discharge process), in addition, waste heat of exhaust steam during power generation is stored using low-temperature heat storage tank.In off-peak electricity consumption period, as much steam as possible is extracted for heat storage, and heat pump is driven using more generated electricity to supply heat using waste heat of exhaust steam and waste heat stored during peak period, and excess high-temperature heat is stored (charging process).In this way, the heating capacity is improved, and the deep peak regulation of electricity is realized, and the entire heat and power cogeneration system can be flexibly adjusted and operated according to the changes of heat and electricity load. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0011] Figure 1 It is a schematic diagram of a heat and power cogeneration system for realizing flexible peak regulation of nuclear power unit provided by the embodiment of the present application.

[0012] Reference signs:

[0013] 1-steam turbine; 2-condenser; 3-steam-water heat exchanger; 4-heat pump unit; 5-low-temperature heat storage tank; 6-medium-temperature heat storage tank; 7-high-temperature heat storage tank; 8-ORC generator unit;

[0014] 301, 302, 303, 304, 401, 402, 403, 404, 405, 406, 501, 502, 601, 701, 801, 802, 901, 902-regulating valve. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application.

[0016] As Figure 1As shown, the heat and power cogeneration system for realizing flexible peak regulation of nuclear power unit provided by the embodiment of the present application comprises a steam turbine 1, a condenser 2, a steam-water heat exchanger 3, a heat pump unit 4, a low-temperature heat storage tank 5, a medium-temperature heat storage tank 6, a high-temperature heat storage tank 7 and an ORC power unit 8, the steam turbine 1 is connected with the steam side inlet and outlet of the steam-water heat exchanger 3 through a steam extraction pipeline and a drain pipeline, the exhaust steam pipeline of the steam turbine 1 is connected with the condenser 2, the condenser 2 is connected with the evaporator side inlet and outlet of the heat pump unit 4 and the inlet and outlet of the low-temperature heat storage tank 5 through a cooling circulating water pipeline, the condenser side inlet of the heat pump unit 4 is connected with a hot water return pipeline, the condenser side outlet is connected with a hot water supply pipeline and the water side inlet pipeline of the steam-water heat exchanger 3, the inlet and outlet pipelines of the medium-temperature heat storage tank 6 are connected with the hot water return pipeline, the water side inlet pipeline of the steam-water heat exchanger 3 and the evaporator side outlet pipeline of the ORC power unit 8, and the inlet and outlet pipelines of the high-temperature heat storage tank 7 are connected with the water side outlet pipeline of the steam-water heat exchanger 3, the hot water supply pipeline and the evaporator side inlet pipeline of the ORC power unit 8.

[0017] In the embodiment, heat and electricity are decoupled by heat storage, the waste heat of the power plant is comprehensively recovered, the heat pump is used to realize the conversion of electricity and heat, and the ORC power unit is coupled to assist the peak regulation of electric power. During the peak period of electricity consumption, the nuclear power unit generates electricity at full capacity, the high-temperature heat storage tank is used as a high-temperature heat source to drive the ORC unit to generate electricity or supply heat to the outside, the hot water is returned to the medium-temperature heat storage tank for storage after the heat is released (discharge process), and the waste heat of the exhaust steam during electricity generation is stored in the low-temperature heat storage tank. During the valley period of electricity consumption, as much steam as possible is extracted for heat storage, and the heat pump is driven by the generated electricity to supply heat after the waste heat of the exhaust steam and the waste heat stored during the peak period are raised in temperature by the heat pump, and the excess high-temperature heat is stored (charging process). In this way, the heat supply capacity is improved, and the peak regulation of electricity is realized. The entire heat and power cogeneration system can be flexibly adjusted and operated according to the changes of the heat and electricity loads.

[0018] In one embodiment of the present application, the steam extraction pipeline, the drain pipeline, the water side inlet and outlet pipelines of the steam-water heat exchanger 3, the cooling circulating water pipeline, the evaporator side inlet and outlet pipelines of the heat pump unit 4, the condenser side inlet and outlet pipelines of the heat pump unit 4, the hot water supply pipeline, the hot water return pipeline, the inlet and outlet pipelines of the medium-temperature heat storage tank 6, the inlet and outlet pipelines of the high-temperature heat storage tank 7 and the evaporator side inlet and outlet pipelines of the ORC power unit 8 are all provided with adjusting valves (i.e. Figure 1 The adjusting valves with reference numerals 301, 302, 303, 304, 401, 402, 403, 404, 405, 406, 501, 502, 601, 701, 801, 802, 901 and 902).

[0019] In one embodiment of the present application, the water temperature of the low-temperature heat storage tank 5 is 20-40℃, the water temperature of the medium-temperature heat storage tank 6 is 60-80℃, and the water temperature of the high-temperature heat storage tank 7 is 120-150℃.

[0020] For example, during the power consumption peak period, high-temperature steam at about 260℃ expands in the steam turbine to do work and drive the generator to generate electricity, the exhaust steam discharged from the steam turbine enters the condenser to be condensed, the heat of condensation is taken away by the cooling circulating water, the temperature of the circulating water is about 20-40℃, and this part of waste heat is stored in the low-temperature heat storage tank as a low-temperature heat source for the heat pump unit for recovery and utilization during the power consumption valley period. Further, the high-temperature heat storage tank can be used as a high-temperature heat source to drive the ORC unit to generate electricity or supply high-temperature hot water according to the demand of the thermal power load.

[0021] During the power consumption valley period, as much steam as possible is extracted and as little electricity as possible is generated, the extraction temperature is about 170℃, the steam passes through the steam-water heat exchanger to heat the medium-temperature hot water in the medium-temperature heat storage tank 6 to 120-150℃, and is stored in the high-temperature heat storage tank. Further, the generated electricity drives the heat pump unit to recover the heat of the exhaust steam of the steam turbine and the low-temperature waste heat stored during the power consumption peak period, and the temperature of the hot water is increased from 50-60℃ to 80-95℃, which can be directly used for heating hot water, or is further introduced into the steam-water heat exchanger to be heated by steam to 120-150℃, and is used for municipal heating or other industrial heat, and the excess high-temperature heat is stored in the high-temperature heat storage tank.

[0022] In addition, the embodiment of the present application also provides a combined heat and power method for realizing flexible peak regulation of a nuclear power unit, which is applied to the method mentioned in the embodiment and includes the following steps.

[0023] During the power consumption peak period, the adjusting valves (i.e., adjusting valves 301, 302, 303, 304, 401, 402, 403 and 404) of the extraction steam pipeline, the drain pipeline, the water inlet and outlet pipelines of the water side of the steam-water heat exchanger 3, the evaporator side and the condenser side of the heat pump unit 4 are closed, the adjusting valves (i.e., adjusting valves 501 and 502) of the water inlet and outlet pipelines of the low-temperature heat storage tank 5 are opened, at this time, the nuclear power unit generates electricity at full capacity, the waste heat of the exhaust steam after the steam turbine 1 generates electricity is stored in the low-temperature heat storage tank 5 through the condenser 2 and the cooling circulating water pipeline;

[0024] During the off-peak period, open the regulating valves (i.e., regulating valves 301, 302, 303, 304, 401, 402, 403, and 404) of the extraction pipe, the drainage pipe, the water side inlet and outlet pipe of the steam-water heat exchanger 3, the evaporator side inlet and outlet pipe and the condenser side inlet and outlet pipe of the heat pump unit 4, close the regulating valves (i.e., regulating valves 801 and 802) of the evaporator side inlet and outlet pipe of the ORC generator unit 8, the high-temperature steam extracted by the steam turbine 1 enters the steam-water heat exchanger 3 through the extraction pipe, heats the outlet water of the medium-temperature thermal storage tank 6, returns to the exhaust pipe of the steam turbine 1, and enters the condenser 2 to continue cooling and temperature reduction, the heat of the high-temperature steam is stored into the high-temperature thermal storage tank 7 through the steam-water heat exchanger 3, the waste heat of the exhaust steam is exchanged to the cooling circulating water through the condenser 2, and the heat stored in the low-temperature thermal storage tank 5 is released at the same time, which is recovered as the low-temperature heat source of the heat pump unit 4.

[0025] In an embodiment of the present application, further comprising:

[0026] During the peak period, according to the demand of the thermal power load of the nuclear power unit, the opening degrees of the regulating valves (i.e., regulating valves 801, 802, 901, and 902) of the evaporator side inlet and outlet pipe, the hot water supply pipe, and the hot water return pipe of the ORC generator unit 8 are controlled, the high-temperature thermal storage tank 7 is used as the high-temperature heat source to drive the ORC generator unit 8 to generate power or supply high-temperature hot water, and the hot water returns to the medium-temperature thermal storage tank 6 for storage after the heat is released.

[0027] In an embodiment of the present application, further comprising:

[0028] During the off-peak period, according to the demand of the thermal power load of the nuclear power unit, the opening degrees of the regulating valves (i.e., regulating valves 601, 701, 901, and 902) of the medium-temperature thermal storage tank 6 inlet and outlet pipe, the high-temperature thermal storage tank 7 inlet and outlet pipe, the hot water supply pipe, and the hot water return pipe are controlled, and the proportion of heat supply and energy storage is adjusted.

[0029] In an embodiment of the present application, further comprising:

[0030] During the off-peak period, the opening degrees of the regulating valves (i.e., regulating valves 404, 405, and 406) of the condenser side outlet pipe of the heat pump unit 4 and the pipe connected with the water side inlet and outlet pipe of the steam-water heat exchanger 3 are controlled, and the supply temperature of the hot water is adjusted.

[0031] In summary, the present application has the following beneficial effects:

[0032] 1) According to the principle of temperature matching and energy cascade utilization, the present application couples the heat pump energy storage and the ORC power generation device matched with the steam parameters of the nuclear power unit, realizes the flexible peak shaving of the nuclear power unit, realizes the heat and electricity decoupling during the combined heat and power generation, fully recovers the waste heat of the exhaust steam of the steam turbine, and improves the comprehensive utilization efficiency of nuclear energy.

[0033] 2) The application can flexibly adjust the power generation and heat supply according to the change of heat and electric load, the maximum power generation capacity is increased by 15% in the peak period of electricity consumption, the maximum heat supply capacity is increased by 30% compared with the steam extraction heat supply, and in the valley period of electricity consumption, the on-grid power can be zero, which avoids the waste of nuclear power resources, realizes the peak shaving of electricity on the basis of ensuring the safety of nuclear power, and improves the economic benefit of the nuclear power plant.

[0034] It should be noted that, in this text, relational terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual such relationship or order between or among the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or equipment including the element.

[0035] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for achieving flexible peaking of a nuclear power plant, the method comprising: The application is applied to a combined heat and power system, and the combined heat and power system is characterized in that it comprises a steam turbine (1), a condenser (2), a steam-water heat exchanger (3), a heat pump unit (4), a low-temperature heat storage tank (5), a medium-temperature heat storage tank (6), a high-temperature heat storage tank (7) and an ORC generator set (8), the steam turbine (1) is connected with the steam inlet and outlet of the steam side of the steam-water heat exchanger (3) through a steam extraction pipeline and a drain pipeline, the exhaust steam pipeline of the steam turbine (1) is connected with the condenser (2), the condenser (2) is connected with the evaporator side inlet and outlet of the heat pump unit (4) and the inlet and outlet of the low-temperature heat storage tank (5) through a cooling circulating water pipeline, the condenser side water inlet of the heat pump unit (4) is connected with a hot water return pipeline, the condenser side water outlet is connected with a hot water supply pipeline and the water side inlet of the steam-water heat exchanger (3), the inlet and outlet of the medium-temperature heat storage tank (6) are connected with the hot water return pipeline, the water side inlet of the steam-water heat exchanger (3) and the evaporator side water outlet of the ORC generator set (8), and the inlet and outlet of the high-temperature heat storage tank (7) are connected with the water side outlet of the steam-water heat exchanger (3), the hot water supply pipeline and the evaporator side water inlet of the ORC generator set (8); ​ The steam extraction pipeline, the drain pipeline, the water side inlet and outlet of the steam-water heat exchanger (3), the cooling circulating water pipeline, the evaporator side inlet and outlet of the heat pump unit (4), the condenser side inlet and outlet of the heat pump unit (4), the hot water supply pipeline, the hot water return pipeline, the inlet and outlet of the medium-temperature heat storage tank (6), the inlet and outlet of the high-temperature heat storage tank (7) and the evaporator side inlet and outlet of the ORC generator set (8) are all provided with adjusting valves for adjusting flow; The water temperature of the low-temperature heat storage tank (5) is 20-40 DEG C, the water temperature of the medium-temperature heat storage tank (6) is 60-80 DEG C, and the water temperature of the high-temperature heat storage tank (7) is 120-150 DEG C The method comprises: During a power consumption peak period, the adjusting valves of the steam extraction pipeline, the drain pipeline, the water side inlet and outlet of the steam-water heat exchanger (3), the evaporator side inlet and outlet of the heat pump unit (4) and the condenser side inlet and outlet of the heat pump unit (4) are closed, and the adjusting valves of the inlet and outlet of the low-temperature heat storage tank (5) are opened, at this time, the nuclear power generator set generates power at full capacity, and the waste heat of the exhaust steam of the steam turbine (1) after power generation is stored into the low-temperature heat storage tank (5) through heat exchange of the condenser (2) and the cooling circulating water pipeline. In the off-peak period, open the regulating valve of the extraction pipe, the drain pipe, the water side inlet and outlet pipe of the steam-water heat exchanger (3), the evaporator side inlet and outlet pipe and the condenser side inlet and outlet pipe of the heat pump unit (4), close the regulating valve of the evaporator side inlet and outlet pipe of the ORC generator (8), the high temperature steam extracted by the steam turbine (1) enters the steam-water heat exchanger (3) through the extraction pipe, heats the outlet water of the medium temperature thermal storage tank (6), returns to the exhaust pipe of the steam turbine (1) and enters the condenser (2) for further cooling, the heat of the high temperature steam is stored in the high temperature thermal storage tank (7) through the steam-water heat exchanger (3), the waste heat of the exhaust steam is exchanged to the cooling circulating water through the condenser (2), at the same time, the heat stored in the low temperature thermal storage tank (5) is released, which is recovered as the low temperature heat source of the heat pump unit (4).

2. The method of claim 1, wherein, Also includes: In the peak period, according to the demand of the thermal load of the nuclear power unit, control the opening degree of the regulating valve of the evaporator side inlet and outlet pipe, the hot water supply pipe and the hot water return pipe of the ORC generator (8), drive the ORC generator (8) to generate electricity or supply high temperature hot water with the high temperature thermal storage tank (7) as the high temperature heat source, and the hot water returns to the medium temperature thermal storage tank (6) after heat release.

3. The method of claim 2, wherein, Also includes: In the off-peak period, according to the demand of the thermal load of the nuclear power unit, control the opening degree of the regulating valve of the medium temperature thermal storage tank (6) inlet and outlet pipe, the high temperature thermal storage tank (7) inlet and outlet pipe, the hot water supply pipe and the hot water return pipe, adjust the proportion of heat supply and energy storage, and the outlet water of the medium temperature thermal storage tank (6) and the hot water return pipe become high temperature hot water after being gradually heated by the heat pump unit (4) and the steam-water heat exchanger (3), part of the high temperature hot water is stored in the high temperature thermal storage tank (7), and the other part returns to the hot water supply.

4. The method of claim 3, wherein, Also includes: In the off-peak period, control the opening degree of the regulating valve of the condenser side outlet pipe of the heat pump unit (4) and the pipe connected with the water side inlet and outlet pipe of the steam-water heat exchanger (3), and adjust the supply temperature of the hot water.

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